The present invention relates to a method of removing a thermal sprayed wear resistant coating from a gas turbine engine part, and an apparatus for doing the same. More particularly, the present invention relates to a method of removing a thermal sprayed wear resistant coating from a gas turbine engine part with a superabrasive grinding wheel.
A gas turbine engine part formed of a metal alloy, such as brush seal components, blade outer air seals, blades, and vanes, may be damaged during use. For example, during operation, the gas turbine engine part may be exposed to high pressure, foreign particles, or in the case of a rotating component, centrifugal force in a hot corrosive environment. In order to help protect the metal alloy from damage, a gas turbine engine part may be coated with a thermal sprayed wear resistant coating (“coating”), such as a high velocity oxy-fuel (HVOF) coating. When a part is manufactured, the metal alloy component of the part may be formed in a smaller dimension than desired, and the coating may then be applied to the metal alloy in a thickness that gives the final part its desired (or “finished”) dimension.
Over time, the coating may become worn (or “eroded”), which may affect the dimensions and performance of the part. The change in dimensions may be a concern for parts that require precise dimensions, such as a brush seal, where it is preferred that bristles remain in contact with a rigid, rotating member in order for the seal to be close-fitting and to discourage airflow through the seal. If the coating on a rotating member of a brush seal becomes worn, a leakage path may form, which could compromise the effectiveness of the brush seal.
When a gas turbine part is repaired, whether to correct the erosion of the coating or to repair the underlying metal alloy component, at least a part of the coating is typically removed. The present invention is a method of removing the thermal sprayed wear resistant coating from a gas turbine engine part.